In our truly global society, more and more people are becoming interconnected with one another through telecommunications systems. Although submarine fiber-optic cable communications systems are but one type of telecommunication system, submarine fiber-optic cables are capable of carrying a greater number of data and voice transmissions than traditional submarine cable systems or modern satellite communication systems.
Stretching thousands of miles across the oceans, submarine fiber-optic cables lie on the ocean's floor, thousands of feet below sea level. Because no one cable could be made that extended thousands of miles in length, submarine fiber-optic cable communication systems are comprised of a series of submarine fiber-optic cables that are spliced together at cable joints. In this manner, many individual cables can be connected to form a single cable of the required length.
If one were to cut open a standard "nonarmored" fiber-optic cable, he would see that each cable is comprised of a series of optic fibers clustered around a steel "king" wire. Together, these wires form the fiber-optic "core" of the wire. The fiber-optic core is then surrounded by steel strength members and two watertight, insulating jackets (an inner copper jacket and an outer polyethylene jacket) encase the entire assembly. The function of the optic fibers is to carry the data and voice transmissions sent over the fiber-optic cable; the steel wires carry any loads placed upon the cable and, in conjunction with the insulating jackets, give the cable its rigidity. Because excess residual strain on the optic fibers may result in undesirable static fatigue and crack growth in the fibers, it is important that the amount of permanent load on the optic fibers (i.e., sustained loads over long periods of time) be minimized. Minimizing the amount of permanent load will prevent excess residual strain from developing in the optic fibers and thus will protect the fibers from damage. Accordingly, it is important that the optic fibers of a fiber-optic cable be protected against permanent loading and excess residual strain.
The cable joints themselves, however, are subject to a considerable amount of potentially harmful loads. For example, when the cable is first being lowered onto the ocean floor, a large tension load is created in the cable by the weight of the many thousands of feet of additional cable below it. In addition, once the cable reaches the desired location, the hydrostatic pressure at that depth can create upwards of 10,000 psi of compression on the cable joint. Because any one of these loads could result in an expensive failure in the fiber-optic cable communication system, it has always been a priority to design cable joints in such a way that when a load is placed upon one cable, the load can be successfully transferred to the other cable without putting stress on the interconnected optic fibers of the two cables.
Traditionally, cable joints were formed by "terminating" the two cables in separate terminating sockets and connecting the two terminating sockets with a load-bearing fiber storage tray or cylinder. The individual optic fibers were then spliced together and secured in the storage tray. The entire subassembly was then covered with a steel jacket and the entire assembly was "insulated" with heat-shrink insulation to keep it waterproof and electrically isolated.
Cable terminating technology is well-known in the prior art. The idea behind cable terminating is to secure the load-bearing steel members of a fiber optic cable, including both the steel strength members and the steel king wire, to a terminating socket assembly so that any load placed upon the steel members would be transferred to the terminating socket assembly. The fragile optic fibers of the cable, however, would completely pass through the terminating socket assembly.
Typically one terminates the steel strength members by first stripping off the cable's protective insulation, separating the strength members from the fiber-optic core, and slipping both the steel members and the core through the center of a terminating socket. A copper jacket and a steel plug is then placed over the core and the steel plug is firmly wedged into the terminating socket. In this way, the steel strength members are secured against the interior surface of the terminating socket while the fiber-optic core passes freely through the socket. To terminate the steel king wire, one merely needs to separate the individual optic fibers from the king wire and to attach the king wire to a king wire clamp assembly. The king wire clamp assembly is usually connected to the terminating socket (although it may be connected to a load-bearing fiber storage tray that is attached to the terminating socket) and together the terminating socket and the king wire clamp assembly form the terminating socket assembly. The end result of this process is that all load-bearing steel members of the fiber-optic cable are secured to the terminating socket assembly.
In a typical cable joint, a load-bearing fiber storage tray or cylinder connects the two terminating socket assemblies. This arrangement is intuitive because the fiber storage tray of a cable joint is in longitudinal alignment with both fiber-optic cables. Given these conditions, if one were to firmly attach the storage tray to both terminating socket assemblies, any force acting on one component of the assembly would act on all of the components. Thus, with this type of cable joint design, any load placed upon the first cable is transferred to its terminating socket assembly, through the fiber storage tray to the other terminating socket assembly, and ultimately to the other cable. The load-bearing fiber storage tray is usually connected to both terminating socket assemblies by means of screws, locking rings, or welds.
The disadvantage of this configuration, however, is that the load-bearing fiber storage tray or cylinder used in the cable joint must be of sufficient mass and strength to resist any loads that pass through it. Thus, such a component is usually quite bulky and made out of hardened steel. Furthermore, due to the strength that must be built into load-bearing fiber storage trays, fiber-to-fiber connections (i.e., two optic fibers spliced together) are usually stored on only one side of the tray; the structural integrity of the storage tray may be compromised if both sides of the tray are channeled out so as to accommodate traditional fiber-storing methods. Using only one side of the storage tray, however, decreases the total amount of fiber-to-fiber splices that can be stored in the fiber storage tray.